Production of delayed pulses



April 1, 1947; 1 TOURSHOU 2,418,375

PRODUCTION OF DELAYED PULSES Filed Nov. 6, 1944 I N VEN T OR. 5117160); 1.161055%;

Patented Apr. 1, 1947 PRODUCTION OF DELAYED PULSES Simeon I. Tourshou, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application November 6, 1944, Serial No. 562,203

1 Claim.

My invention relates to the production of electrical pulses and particularly to the production of pulses that are delayed an adjustable amount with respect to other pulses such as driving or control pulses.

An object of the invention is to provide an improved method of and means for producing an electrical pulse that is delayed with respect to another pulse.

Another object of the invention is to provide an improved method of and means for delaying an electrical pulse an adjustable amount.

According to one preferred embodiment of the invention, a vacuum tube is provided with a tuned anode circuit whichv is shock excited by applying to the grid of the tube the pulse that is to be delayed. The resulting clamped wave appearing across the tuned circuit is applied to the grid of a Thyratron or the like whereby the second half cycle of the wave, which is a positive half cycle, triggers the Thyratron. The resulting sudden flow of Thyratron current produces a pulse across a transformer in the Thyratron anode circuit, this pulse being delayed with respect to the applied pulse slightly more than one half or fractional cycle of the damped wave. Therefore, the amount of the delay may be adjusted by changing the tuning of the tuned cirsuit to change the period of the wave appearing thereacross.

The invention will be-better understood from the following description taken in connection with the accompanying drawing in which Fig. 1 is a circuit diagram of one embodiment of the invention, and

Figs. 2, 3 and 4 are groups of graphs that are referred to in explaining the operation of the circuit shown in Fig. 1.

Referring to the drawing, a pulse generator l supplies periodic electrical pulses A which are to appear in delayed and amplified form as the pulses B at the output terminals of my improved circuit. The pulses A are applied to the grid of a vacuum tube H which has a tunable anode circuit comprising a variable capacitor [2 and a variable inductor i3.

Each pulse A shock excites the tuned circuit l2-l3 whereby a damped wave E (Fig. 2) appears thereacross. Since the pulse A is of positive polarity at the grid of tube II, the first half cycle or fractional cycle of the Wave E is negative. Whether the first negative swing of the wave E is substantially a full half cycle or is a smaller fraction of a cycle depends upon the 2 width of the pulse A as will be explained hereinafter.

The wave E is applied to the control grid I4 of a gas or vapor tube It such as a Thyratron so that the tube it is ionized or ignited shortly after the start of the first positive half cycle of the wave E when the Wave reaches the ignition voltage value indicated by the broken line ll in Fig. 2.

The wave E may be applied to the grid Id of tube l6 through a blocking capacitor l8 and a grid protective resistor IS. A suitable operating bias is applied through a grid resistor 20 to the grid M from a cathode resistor 2| shunted by a capacitor 22. A positive D.-C. voltage is applied to the anode 23 through an anode resistor 24.

The anode circuit of the vapor tube I6 includes the primary winding 25 of a transformer 21, the high potential end of winding 26 being connected to the anode 23 through a capacitor 28. Leakage inductance of the transformer 21 is represented at 2B. A delayed pulse B appears across the secondary winding 3! of the transformer 21 each time the tube 16 is ignited. It will be evident from an inspection of Fig. 2 that the amount that the pulse B is delayed with respect to the pulse A depends upon the period of the wave E and, therefore, upon the tuning of the circuit 12-43.

The circuit operation will now be described in more detail. The pulse A shock excites the tuned circuit 12-43 to produce a damped wave: E which preferably dies down before the next pulse A occurs. The second half cycle of the wave E triggers the vapor tube 16. The resulting sudden fiow of anode current through the tube l6 causes a pulse of current through the primary winding 26 which induces the voltage pulse B in the secondary winding 3!. Thus, there is produced a delayed pulse B, the amount of delay for a pulse A of given width or duration being determined by the frequency to which the circuit l2-l3 is tuned.

The vapor tube 16 is deionized or extinguished before the occurrence of the next pulse A by the charge left on the capacitor 28 at the end of the pulse B. This action is as follows: The sudden fiow of current through the primary winding 26 and the tube It when the tube I6 is ignited puts a D.-C. charge on the capacitor 28 making its terminal on the anode side of negative polarity. At the end of this sudden flow of current, the voltage across the capacitor 28 lowers the potential on the anode 23 sufficiently to extinguish the tube [6. By the time the next pulse A occurs, enough of the charge has leaked off the capacitor 23 so that the action may be repeated.

As previously mentioned, the duration of the first negative swing of the wave E depends upon the width or duration of the applied pulse A. If the pulse A is short compared with the period of the tuned circuit l2-l3, the first negative swing of the wave E will be approximately one quarter cycle in duration as illustrated in Fig. 3. If the pulse A is a little longer, the first negative swing will be closer to one half cycle in duration as shown in Fig. 4:. In Fig. 2, it is assumed that the pulse A is long enough to i'nake the first negative swing substantially a full half cycle. For any given Width of the pulse A, the pulse B may be delayed the desired amount by adjusting the tuning of the circuit l2l3.

I claim as my invention:

'In combination. a vacuum tube having a control grid and having a tuned anode circuit, means for applying a positive pulse to said grid whereby said tuned circuit is shock excited to produce a damped wave thereacross having a negative first 4 fractional cycle, and means responsive to the voltage rise of the following positive half cycle of said damped wave for producing a pulse that is delayed with respect to the pulse applied to said grid, said last means including a gas or vapor tube having a control grid to which said damped wave is applied and having an anode circuit that includes an anode resistor through which an operating voltage is applied to said anode, a transformer across which said delayed pulse appears, said transformer being connected across said anode circuit through a capacitor which charges periodically to extinguish said vapor tube and which discharges periodically The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Nichols Apr. 4, 1939 Number 

